Hassan Muhammad, Sadiq Mohammad Ali, Halim Muhammad Sohail, Afridi Rubbia, Soliman Mohamed K, Sarwar Salman, Agarwal Aniruddha, Do Diana V, Nguyen Quan Dong, Sepah Yasir Jamal
Department of Ophthalmology, Byers Eye Institute, Stanford University, Palo Alto, CA 94303 USA.
Ocular Imaging Research and Reading Center, Menlo Park, CA USA.
Int J Retina Vitreous. 2017 Jul 31;3:27. doi: 10.1186/s40942-017-0080-0. eCollection 2017.
To assess normal vessel flow density (VFD) in macular and peripapillary regions of eyes with no known ocular pathology using optical coherence tomography angiography (OCTA).
AngioVue (Optovue, Fremont, CA, USA) was used to capture OCTA images. A 3 × 3 mm grid and a 4.5 × 4.5 mm grid was used to scan parafoveal and peripapillary regions, respectively. ReVue software was utilized to measure VFD in five sectors within the inner two circles of ETDRS grid in macular region and correlated to retinal thickness of same sectors. At optic disc, VFD was calculated in six sectors based on Garway-Heath map. Area and morphology of foveal avascular zone (FAZ) was correlated with VFD in central 1 mm. The influence of myopia on mean VFD was also assessed.
Twenty-four eyes (mean age: 30 years) were analyzed. Mean VFD in macular sectors was 43.5 (±4.5) and 45.8 (±5.0) % in superficial and deep retinal plexuses, respectively. Mean VFD was significantly higher in deep retinal plexus compared to superficial retinal plexus in all sectors except central 1 mm (p < 0.05). Mean VFD in central 1 mm increases with an increase in central retinal thickness in both superficial and deep retinal plexuses (p < 0.001). Mean parafoveal VFD at level of both superficial and deep retinal plexuses decrease with an increase in spherical equivalent in myopics (p < 0.05). Mean VFD in myopics was found to be significantly lower in parafoveal region of deep retinal plexus (p < 0.05). Mean area of FAZ was 0.33 (±0.15) and 0.47 mm (±0.15) in superficial and deep retinal plexuses, respectively. Area of FAZ decreases with an increase in central 1 mm thickness and foveal VFD (p < 0.001).
OCTA may be used to measure VFD in macular and peripapillary regions. Vessels in the parafoveal region are more densely packed in the deep retinal plexus leading to higher VFD compared to superficial plexus. Thicker retina in fovea translates into higher foveal VFD due to more compact arrangement of retinal layers and continuity of inner nuclear layer (INL). Myopia is associated with lower VFD in parafoveal region at level of deep retinal plexuses which may explain thinning of INL in myopics.
使用光学相干断层扫描血管造影（OCTA）评估无已知眼部病变的眼睛黄斑和视乳头周围区域的正常血管血流密度（VFD）。
使用AngioVue（美国加利福尼亚州弗里蒙特市Optovue公司）采集OCTA图像。分别使用3×3mm网格和4.5×4.5mm网格扫描黄斑旁和视乳头周围区域。利用ReVue软件测量黄斑区域ETDRS网格内两个同心圆中五个扇区的VFD，并与相同扇区的视网膜厚度相关联。在视盘处，根据Garway-Heath地图在六个扇区中计算VFD。黄斑无血管区（FAZ）的面积和形态与中心1mm区域的VFD相关。还评估了近视对平均VFD的影响。
分析了24只眼（平均年龄：30岁）。黄斑扇区浅层和深层视网膜丛的平均VFD分别为43.5（±4.5）%和45.8（±5.0）%。除中心1mm区域外，所有扇区深层视网膜丛的平均VFD均显著高于浅层视网膜丛（p<0.05）。浅层和深层视网膜丛中心1mm区域的平均VFD均随中心视网膜厚度增加而增加（p<0.001）。近视眼中，浅层和深层视网膜丛水平的黄斑旁平均VFD均随球镜等效度增加而降低（p<0.05）。发现近视眼中深层视网膜丛黄斑旁区域的平均VFD显著较低（p<0.05）。浅层和深层视网膜丛中FAZ的平均面积分别为0.33（±0.15）和0.47mm（±0.15）。FAZ面积随中心1mm厚度和黄斑VFD增加而减小（p<0.001）。
OCTA可用于测量黄斑和视乳头周围区域的VFD。与浅层丛相比，黄斑旁区域深层视网膜丛中的血管分布更密集，导致VFD更高。由于视网膜层排列更紧密且内核层（INL）连续，黄斑区视网膜越厚，黄斑VFD越高。近视与深层视网膜丛水平的黄斑旁区域VFD较低有关，这可能解释了近视眼中INL变薄的原因。
